Carton flap-opening apparatus



July 21, 1964 B. J. ARNETT CARTON FLAP-OPENING APPARATUS 3 Sheets-Sheet 2 INVENTOR. BOYD J A/PNETT Filed Jan. 16, 1961 "TW N ow Q Q KO w PATENT AGE/VT July 21, 1964 TT 3,141,279

CARTON FLAP-OPENING APPARATUS Filed Jan. 16, 1961 3 Sheets-Sheet 3 F/GL 3A FIG... 3B

INVENTOR. BOYD .J ARNETT PATENT AGENT 3,141,279 CARTGN FLAP-OPENING- APPARATUS Boyd J. Arnett, 1914 Monroe St., Santa Clara, Calif. Filed Jan. 16, 1961, Ser. No. 82,974 3 Ciairns. (Cl. 53-382) The present invention relates to the art of article handling and more particularly to apparatus for opening the unsealed side and end flaps of cardboard cartons or other containers.

Bottles, cans and other articles are conventionally packed for ease of handling and shipment in cardboard cartons or other generally similar containers having inner end flaps and outer side flaps which are sealed after the carton has been loaded. Obviously, in order to load the carton, initially the flaps must be opened and thereafter held in the open disposition during the entire loading operation. Preparatory to the loading operation in the conventional carton loading machine, the carton is manually grasped, the flaps manually opened, and the opened carton then placed on the entrance end of the conveyor utilized to transport the carton through the loading cycle. Since presently utilized carton loading machines operate at relatively high speeds, the operator performing the manual flap-opening and feeding operation must work quickly yet accurately to insure the proper feed disposition of the carton and the simultaneous complete opening of all four flaps. Working rapidly and continuously over an extended period of time, errors in the manual feed arise which can result in jamming of the apparatus and partial destruction of the carton. Either result obviously reduces the output of the apparatus to a degree extremely deleterious to the desired high rate of production.

Accordingly, it is a general object of the present invention to provide apparatus for automatically opening all flaps of a carton and for feeding the carton toward a loading apparatus with the flaps retained in the desired opened disposition and the carton itself properly disposed for subsequent reception of its load or contents.

More specifically, it is a feature of the present invention to provide a carton flap-opening apparatus wherein the disposition of the carton during the entire flap-opening process is not varied or changed; wherefore, ultimately, rapidity of operation is achievable.

Another feature relates to the precise disposition of the flap-opening elements whereby the flaps themselves are engaged but the carton body is not, thus precluding the possibility of jamming.

Additionally, it is a feature or" the invention to provide a carton flap-opening apparatus wherein the conveyor mechanism acts to assure proper carton disposition during the enitre flap-opening process, and furthermore, initiates such fiap-opening process.

Another feature of the invention relates to the automatic opening of the carton flaps in direct response to the presence of a carton at a particular position in the apparatus.

Yet a further feature of the invention relates to a carton flap-opening apparatus which is arranged to provide for quick and easy adjustability to accommodate cartons of widely variant dimensions.

These, as well as additional objects and features of the invention will become more apparent from a perusal of the following description of the apparatus illustrated in the accompanying drawings wherein:

FIG. 1 is a top plan view of an apparatus embodying the present invention,

FIG. 2 is an enlarged transverse sectional view taken substantially along line 2-2 of FIG. 1 and FIGS. 3A and 3B are longitudinal sectional views taken along lines 3A-3A and 3B-3B of FIG. 1 and illustrating respectively operation of the mechanisms for opening the leading and trailing end flaps of a carton.

States Patent Generally, the apparatus embodying the present invention includes means for conveying a carton in upright disposition with its inner end flaps and outer side flaps along a predetermined path in closed, but unsealed dispositions. During its travel, the outer side flaps are first opened; the trailing end flap and the leading end fiap are then, in turn, opened wherefore the carton may be delivered to a carton loading apparatus ready for the reception of bottles or other contents.

More particularly, as shown in the drawings, the apparatus generally includes a pair of rather squat laterally spaced, hollow standards 10, 10' which support therebetween the means for conveying the cartons along a predetermined path plus the individual flap-opening mechanisms disposed at intervals along such path. The standards 10, 10' are arranged in substantially mirror symmetry on opposite sides of the desired carton path and thus, like other duplicate elements of the apparatus, are differentiated merely by addition of the prime notation to the identifying numeral. Each standard 10 supports within its hollow interior two spaced vertically-disposed threaded rods 12, 14, each of which is rotatably supported at its upper and lower ends on suitable bearings 16, 18 fixed in vertical alignment on the standards, as best illustrated in FIG. 2. Two of the vertically disposed adjustment rods 12, 12 which are directly opposite one another pass through threaded openings in the opposite ends of a transversely-disposed support member 20 which accordingly bridges the space between the standards it), 10' and will move upwardly or downwardly upon suitable rotation of the adjustment rods. Similarly, the other two adjustment rods 14, 14' mount a second transverse support member 22 (see FIG. 1) in spaced parallelism to that described. These spaced parallel support members 26, 22, in turn, carry parallel channel members 24, 24' that project in both directions from the standards 10, 10' and carry therebetween a plurality of spaced, parallel shafts 26 upon which a plurality of rollers 28 are supported. The rollers 28 jointly serve as the mobile support for the carton during its traverse of the flap-opening apparatus and through appropriate rotation of the vertically-disposed adjustment rods 12, 14, the level of carton support can be adjusted up or down. To facilitate such adjustment, like sprockets 30 are mounted adjacent the lower end of each of the adjustment rods and a sprocket chain 32 is trained about all four sprockets so that upon rotation of an actuating crank 34 attached to the upper end of one of the vertically disposed rods 12, all rods will partake of precisely the same amount of rotation; wherefore not only will the carton-supporting level, defined by the rollers 28, be adjusted upwardly or downwardly, but will remain horizontal as desired.

Each of the transversely disposed and vertically adjustable support members 20, 22 carries adjacent its opposite ends a pair of brackets, as shown at 4t), 40' in FIG. 2, that are slidable along the support member, but always rise substantially vertically upward therefrom. The brackets 40, 40' on the transverse support members adjacent each standard 10, or 10, respectively, carry a longitudinally extending rail 42 or 42'. On each rail 42, a plurality of pulleys 44 are supported for rotation about parallel, vertical axes; each pulley being supported for such rotation at the end of a bracket 46 pivotally supported on the top of the rail 42 and urged inwardly toward the center line of the apparatus by a suitable spring 48. An endless belt 50 is trained over the inwardly-projecting portion of these pulleys 44 and a pair of larger pulleys 52, 54 adjacent the opposite extremities of the supporting rail 42, such belt on each side of the center line being urged by the described spring-urged pulleys 44 into engagement with the sides of a carton disposed on the previously described rollers 28.

The shafts supporting the larger pulleys 52, 52' at the corresponding ends of the respective rails 42, 42' at the left in FIG. 1 also carry sprockets 56, 56 about which are trained a sprocket chain 58 that also is passed around a drive sprocket 60 suitably driven from an electric motor 62 and an idler sprocket 64 carried by a pivoted arm 66 which is urged by a spring 68 in a'direction to constantly maintain tension on the sprocket chain 58 in a generally conventional fashion. The engagement with the driven sprockets 56, 56 at the ends of the two rails 42, 42 is such that energization of the motor 62 will cause the inner flights of the two belts t), 50 to move in the same direction and at the same speed to thus serve as the propulsion mechanism for a carton movably supported on the described rollers 28. Additionally, it is to be noted that the resilient urgency of the propelling belts 50, 50' against the sides of the carton not only serves to maintain the propelling contact therewith, but also forces the sides of the carton slightly inwardly which, in turn, effects a slight opening of the carton flaps to initiate the flap-opening operation, as will become more apparent hereinafter.

While the previously described rollers 28 which support the carton can obviously accommodate cartons of widely Variant widths, lateral adjustment of the propelling belts 50, 50' is necessitated if cartons of such difierent width are to be properly handled thereby. Such adjustment is enabled by the slidable support of the rail-supporting brackets 40, 40' on the transverse support members 29, 22, as previously mentioned, and is accomplished through an adjustment screw 70 or 72 that is mounted immediately above a respective one of said supports 20 or 22 to extend transversely of the longtiudinal direction of the apparatus, as best shown in FIG. 2. Conventionally, the adjustment screw 70 is centrally carried by brackets 76 projecting upwardly from the transverse support member 20 thereunder and the opposite extremities of the adjustment screw are threaded similarly with equal but opposite pitch to pass through appropriate threaded openings in the described slidable brackets 40, 40 that support the rails 42, 42'. Consequently, rotation of the adjustment screw 70 in one direction will move these rails 42, 42 outwardly while rotation in the opposite direction will effect movement of the rails toward one another and thus closer to the longitudinal center line of the apparatus. The adjustment screws 70, 72 above the respective transverse support members 20, 22 are connected by a sprocket chain 78 passing over similar sprockets 80, 82 located substantially centrally of the two screws. As a consequence, adjustment of the rotative disposition of one adjustment screw will effect a correspondent adjustment of the other; wherefore the rails 42, 42 will not only be moved inwardly or outwardly relative to the center line of the apparatus, but will remain in precisely parallel relationship. For any given carton width, these adjustment screws 70, 72 are turned so that slight pressure against the sides of the carton by the conveyor belts 50, 50' is achieved both to provide good resilient, frictional contact for purposes of such conveyance and to provide the slight inward pressure against the sides of the carton to instigate the initial opening of the flaps, as previously mentioned.

The conveyor structure thus far described serves to receive a carton and transport the same along a predetermined path centered at the longitudinal center line of the apparatus and also, as mentioned, initiates partial opening of the flaps of the carton. Consequently, in accordance with the present invention, the flap-opening elements now to be described can be disposed adjacent the path of the main body portion of the carton so that only the flaps are engaged and jamming of the cartons is effectively avoided.

The full opening of the side flaps to substantially horizontally projecting relationship is achieved through engagement with appropriately configured bars 90, 90' constituting extensions of side flap opening rails 92, 92' which are supported in mirror symmetry on opposite sides of the longitudinal center line of the apparatus. Preferably,

such support of the rails 92, 92 is provided as illustrated in FIG. 1 by rods 94, 94', 96, 96' that project inwardly from like tubular sockets 98, 98, 100, ltltl fixed in spaced, parallel relation on the tops of the described standards 10, 1t), and are welded to the side-flap opening rails 92, 92' at their inwardly projecting extremities. When the disposition of the side flap engaging rails 92, 92 must be varied inwardly or outwardly relative to the center line, set screws 102 that normally project through the tubular sockets and engage the supporting rods 94, 94', 96, 96 to fix the same, are temporarily loosened whereupon the side rails 92, 92' can be manually moved to their desired dispositions and the set screws 102 then retightened to maintain such dispositions as long as required.

Throughout their length, these side-flap engaging rails 92, 92 are disposed laterally outward of the main body of a progressing carton as clearly shown in FIG. 2 but adjacent the entrance end of the apparatus, the mentioned extended bars 90, curve inwardly to mount between their projecting extremities a roller 104 just above the central upper surface of the carton body, as can best be visualized by reference to FIGS. 1 and 3A. The projecting bars 90, 90' are firmly supported by the rails 92, 92' but are composed of semi-resilient material so that when the rails are laterally adjusted, as described, the bars can bend slightly to accommodate such adjustment.

The curved bars 90, 90, when supported as described, pass between the upper surface of the carton body and the undersurface of the side flaps which, under the compressing action of the conveyor belts 5t), 50, are urged to a partially opened disposition, as has been previously mentioned. As the carton advance continues, the configuration of the curved bars 90, 90' is such that each of the side flaps is gradually swung through an angle of 180 until an outwardly propecting disposition, as illustrated in FIG. 2, is attained, thus to complete the side flap opening operation during the first several feet of traverse of the apparatus. It is to be particularly observed that these side flap opening rails 92, 92 are completely passive elements and it is the carton motion itself which efiects opening of its own side flaps in the manner indicated.

For purposes of opening of the end flaps of the carton after the side flaps have been opened in the manner indicated, means are provided preferably first for opening the trailing end flap of the carton and thereafter for opening the leading end flap of the carton. The trailing end flap opening means preferably takes the form an arm pivoted about a horizontal axis formed at the lower extremity of an inclined support bracket 112 that is rigidly connected at its upper end to an arched frame member 126 extending over the carton path and supported at each side on the standard 10, 10'. The arm 11!) is supported substantially centrally over the roller conveyor, and as shown in FIG. 3A is urged by gravity downwardly toward a carton thereunder[ A suspension rod 114 is pivotally connected at its lower end to the arm 110 and passes upwardly for sliding movement through an opening in the bracket 112. A nut 116 on the threaded upper end of the suspen sion rod 114 engages the bracket 112 so as to restrict downward swinging movement of the arm 110 to a disposition such that a hooked portion 110a on the arm 110 does not come into engagement with the body portion of the carton but can engage the trailing end flap of the carton which is slightly raised, as shown in FIG. 3A, in a manner similar to the partial opening of the end flaps by the pressure of the conveyor belts 50, 50' against the sides of the carton. After the hooked portion 110a of the arm 110 has been brought into engagement with the trailing end flap of the carton, continued motion of the carton to the left, as viewed in FIG. 3A, will cause the edge of the end flap and the hooked portion of the arm in engagement therewith to move along an upwardly arcuate path, as indicated by the phantom line showing in FIG. 3A so that eventually the trailing end flap of the carton will swing through an angle of substantially 180, or in other words, to a substantially horizontal rearwardly projectiong disposition, also as shown in phantom lines. Preferably, a tail 1101) is provided on the arm 110 beyond the hooked portion 110a to maintain such rearwardly projecting disposition of the trailing end flap as carton motion continues.

Obviously, the described trailing end-flap opening means will accommodate cartons of various lengths or widths without adjustment, and simple turning of the nut 116 on the suspension rod 114 will appropriately support the flap-opening arm 110 for a carton of any height.

Generally, a similar engagement of the edge of the leading end flap of the carton is utilized to achieve opening thereof, but since the carton is continually moved by the conveyor belts 50, 50, the simple carton-actuated opening utilized in the case of the trailing end flap cannot be achieved. An arm 120 having a hooked portion 126a generally similar to that utilized for opening of the trailing end flap of the carton is pivotally supported from the lower end of a lever 122 so as to project downwardly toward the path of carton motion. To maintain the arm 120 in desired flap-engaging position, a suspension rod 132 is pivotally connected to the arm 120 and passes upwardly for slidable movement through an opening in the bracket 122a on the lever 122. A nut 134 limits the downward movement of the arm 120, under force supplied by gravity and supplemented by a coil spring 136 on the rod 132. As illustrated in FIG. 3B, the upper end of the described lever 122 is pivotally supported at a fixed but adjustable position at the end of a rigid bracket 124 which is mounted centrally on the previously described arched frame member 126. A link 128 pivotally connected at one end to the lever 122 beneath its fixed pivotal support in turn is pivotally connected at its other end to a pneumatically-actuated ram 130 of any known commercial variety also carried on the arched frame member 126, as best illustrated in FIG. 1. The link 128 is moved forwardly or rearwardly by the pneumatic ram 130 depending upon electrical energization of its solenoid controlled valve; as the ram is extended from the full-line position in FIG. 3B, the lever 122 is swung in a clockwise direction about its upper fixed pivot and, in turn, effects motion of the attached arm 120 to the left, as viewed in FIG. 3B and at a speed considerably greater than the rate of carton advance. If a carton is positioned with the edge of its leading end flap in proximity to the hooked portion 120a of the arm 126, as shown in full lines in FIG. 3B, such leading end flap will be swung arcuately by the arm 120 first to the upwardly disposed phantom line disposition shown in FIG. 3B and eventually through 180 to the fully-opened disposition. A forwardly-directed tail 120k on the arm 120 maintains the flap in open disposition until the carton has fully passed. The pivoted connection of the arm 120 with the end of the lever 122 allows the arm to move in the required arcuate path automatically accommodating itself to the dimensions of the end flap.

Upon actuation of the pneumatic ram 130 in the opposite direction, the lever 122 will be moved in a counterclockwise direction and the arm 120, in turn, will be moved to the right until a disposition such as illustrated in full lines in FIG. 3B is once again attained; whereupon the leading end flap opening mechanism is prepared for another operation of the described type. A rearwardly-directed curved tail 1200 on the arm 120 engages and guides, in a cam like fashion, the arm over the front edge of a subsequent carton to preclude jamming.

In order to energize the pneumatic ram 130 at the appropriate time in order to engage and open the leading end flap, a normally-open microswitch 136 is supported for longitudinal adjustment on the outside of the one 6 side flap engaging rail 92' so that the switch arm 136a projects into the path of the opened side flap of the advancing carton, as clearly shown in FIG. 2. To assure proper disposition of the carton side flaps for engagement with the microswitch arm 136a, additional rods 140, 140' are supported respectively from the side flap engaging rails 92, 92 to engage the undersurface of the projecting side flaps and hold the same .in horizontally projecting disposition. When the described microswitch arm 1364 is engaged by the flap so as to be closed, the pneumatic ram 130 is, in turn, actuated to move the hooked portion a of the arm into engagement with the edge of the leading end flap and effect opening thereof.

A normally-closed microswitch 142 and a normallyopen microswich 144 are similarly supported from the opposite rail 92 for engagement by the other carton side flap in timed sequence prior to contact of the described microswitch 136. The microswitches 142 and 144 are connected in series in an electrical circuit (not shown) that energizes return stroke of the ram 130. Since the microswitch 142 is normally closed and the microswitch 144 is normally open, the circuit can be completed only when a carton flap has been removed from contact with microswitch 142 but still is contacting the second miscoswitch 144. Such flap disposition occurs only after the ram has eifected opening of the leading end flap because of the position of the microswitches 142, 144 and effects the return stroke of the ram 139 preparatory to a repeated flap-opening operation.

Adjacent the exit end of the apparatus, two additional rods 1st), 156 are supported from the side flap engaging rails 92, 92' at a disposition substantially inwardly thereof so as to come into engagement with the upper surface of all four open flaps and thus serve to maintain such flaps in their open disposition during the remainder of carton travel through the apparatus and into the operatively associated carton loading apparatus (not shown).

The entire operation of the apparatus can now be recapitulated. The carton to be opened is measured and the level of the rollers 28 is first adjusted by turning the crank 34 to effect rotation of the vertically disposed adjustment rods 12, 12', 14, 14 so that the opened side flaps will project substantially horizontally under the side flap engaging rails 92, 92', as indicated in phantom lines in FIG. 2. This provides accommodation for the height of the carton and is the only adjustment necessary for this purpose, as previously mentioned. To accommodate the width of the carton, the adjustment screws 71), 72 are turned until the desired slight pressure against the carton sides by the conveyor belts 50, 50' is achieved. Furthermore, if necessary, the side flap engaging rails 92, 92' may be adjusted inwardly or out wardly to assure their continued contact with the side flaps and the necessary contact with the described microswitches 136, 142 and 144. In turn, to accommodate the length of the carton, the position of such microswitches 136, 142, and 144 longitudinally of the side flap engaging rails 92, 92' is adjusted to assure actuation of the pneumatic ram 131 at the appropriate time to establish hooked engagement with the leading end flap of the carton and subsequent return of the ram, as described.

With such preliminary adjustments made, the motor 62 is energized and the carton is placed at the entrance end of the machine by the attendant. Pressed engagement between the moving belts 5t 50 and the sides of the carton is immediately established to commence conveyance thereof over the supporting rollers 28. At the same time, the pressure applied to the sides of the carton initiates partial opening of the outer side flaps wherefore subsequently the centrally-joined ends of the bars 90, 90' extending from the side flap engaging rails 92, 92' may pass between the upper surface of the carton body and the under surface of the partially opened. side flaps to engage and subsequently open such side flaps as advanc of the carton continues.

After the side flaps have been opened, the carton is brought underneath the first arm 110 which under the action of gravity is brought into contact with the advancing edge of the trailing end flap of the carton to subsequently move such trailing end flap to a rearwardly projecting opened disposition, as shown clearly in FIG. 3A. Thereafter, continued advance of the carton brings the side flaps into engagement with the flap-opening microswitch 136 at a time simultaneous with the passage of the hooked portion 120a of the second arm 120 over the edge of the leading end flap; whereupon actuation of the pneumatic ram 130 is initiated to efiect opening of such leading end flap as illustrated in FIG. 3B. Subsequent removal of the other carton side flap from contact with the second microswitch 142, in turn, energizes the pneumatic ram 130 to return the second arm 120 to its initial position preparatory to repetition of the described leading end flap opening operation. The carton with all four flaps open passes underneath the retaining rods 150, 150' which maintain contact with the upper surfaces of all four flaps until the carton moves from the described flap opening apparatus onto the associated carton loading apparatus.

Various modifications and/or alterations in the described structure can obviously be made without departing from the spirit of the invention; and the foregoing description of one embodiment is to be considered as purely exemplary and not in a limiting sense. The scope of the invention is to be indicated by reference to the appended claims.

What is claimed is:

l. A carton flap opener which comprises means for moving a carton in upright disposition along a predetermined path, an arm supported for pivotal motion about substantially a horizontal aXis above the path of carton motion and adapted to swing downwardly toward such path, said arm having a hooked portion adapted to engage the transversely-disposed edge of one flap of an advancing carton, means supporting said pivotally-supported arm for translatory motion in the direction of carton advance, and means responsive to engagement by the advancing carton to actuate translatory motion of said arm in the direction of carton motion at a speed substantially greater than the speed of carton advance to open the flap.

2. A carton flap opener according to claim 1 which comprises means responsive to engagement by the advancing carton beyond the flap-opening position to actuate translatory motion of said arm in a direction opposite to the direction of carton advance.

3. A carton flap opener according to claim 2 wherein said means for actuating translatory motion of said arm in both directions constitutes a reciprocable pneumatic ram.

4. A carton flap opener which comprises means for moving a carton in upright disposition along a predetermined path with its outer flaps in sidewise relation, means adjacent the path of carton motion adapted to engage and open the carton side flaps to laterally projecting dispositions as the carton advances, means adjacent the carton path for engaging and opening the trailing end flapof the carton in response to further advance of the carton, means for engaging the leading end flap of the carton upon further advance thereof including a member arranged for pivotal and translatory motion in the direc tion of carton motion, and means operative to actuate motion of said leading end flap engaging means in the direction of carton motion at a speed substantially greater than the speed of carton motion thereby to eflFect opening of said leading end flap.

5. A carton flap opener according to claim 4 wherein said actuating means is rendered operative in response to the arrival of a projecting side flap at a predetermined position of carton advance. 6. A carton flap opener according to claim 4 which comprises means operative to actuate motion of said leading end flap engaging means in a direction opposite to the direction of carton motion in response to the arrival of a projecting side flap at a position whereat the leading end flap has been opened.

7. A carton flap opener according to claim 4 which comprises means positioned beyond all of said flap-opening means for engaging the exposed upper surfaces of all opened flaps to retain the same in their opened disposition during further advance of the carton.

8. A carton flap opener which comprises means including a plurality of rollers adapted to support a carton for movement in upright disposition with its outer flaps in sidewise relation, means for engaging the sides of the carton and propelling the same over said supporting rollers along a predetermined path, means including a pair of members projecting angularly over the carton path for engaging and opening the carton side flaps to outwardly projecting dispositions as the carton is advanced over the first ones of said rollers, means including a first hooked member pivotally suspended over the carton path beyond said side flap opening means and urged downward toward a carton passing thereunder for engaging and pulling the trailing end flap of the carton to open disposition as the carton completes its travel thereunder, means operatively associated with said trailing end flap opening means to limit downward movement of said member to a disposition slightly above the upper edge of the main body portion of the carton, means including a second hooked member supported above the carton path beyond said trailing end flap opening means for pivotal and translational movement and adapted to engage and open the leading end flap of the carton, said leading end flap opening means including means operable to move said hooked member along the direction of carton advance at substantially greater speed whereby the leading end flap is opened, and means operative in response to engagement by the advancing carton to actuate movement of said second hooked member.

References Cited in the file of this patent UNITED STATES PATENTS 2,761,263 Bruce Sept. 4, 1956 2,890,560 Nigrelli et a1 June 16, 1959 2,915,868 Copping Dec. 8, 1959 2,918,773 Krupp et al Dec. 29, 1959 2,997,833 Nigrelli et al Aug. 29, 1961 3,068,622 Brownlee Dec. 18, 1962 

1. A CARTON FLAP OPENER WHICH COMPRISES MEANS FOR MOVING A CARTON IN UPRIGHT DISPOSITION ALONG A PREDETERMINED PATH, AN ARM SUPPORTED FOR PIVOTAL MOTION ABOUT SUBSTANTIALLY A HORIZONTAL AXIS ABOVE THE PATH OF CARTON MOTION AND ADAPTED TO SWING DOWNWARDLY TOWARD SUCH PATH, SAID ARM HAVING A HOOKED PORTION ADAPTED TO ENGAGE THE TRANSVERSELY-DISPOSED EDGE OF ONE FLAP OF AN ADVANCING CARTON, MEANS SUPPORTING SAID PIVOTALLY-SUPPORTED ARM FOR TRANSLATORY MOTION IN THE DIRECTION OF CARTON ADVANCE, AND MEANS RESPONSIVE TO ENGAGEMENT BY THE ADVANCING CARTON TO ACTUATE TRANSLATORY MOTION OF SAID ARM IN THE DIRECTION OF CARTON MOTION AT A SPEED SUBSTANTIALLY GREATER THAN THE SPEED OF CARTON ADVANCE TO OPEN THE FLAP. 